Crook (music) - Master Crook and Coupler System

Master Crook and Coupler System

Early horns had unalterable lengths and permanently attached mouthpieces. This presented problems in concert situations. A different horn was required for different keys, and the instrument could not be tuned. Around 1700 the Leichnamschneider brothers in Vienna developed a horn with a removable mouthpiece which could be connected to a short piece of tubing, called a master crook. Additional pieces, couplers, of different length were inserted between the master crook and the body of the horn to change the horn's length, and thus the pitch. For pictures of horns with master crooks and couplers see the online picture gallery of the University of Edinburgh Collection of Historic Musical Instruments (items 3296 and 3297). Fine tuning was done with even shorter segments called tuning bits. This simple and relatively inexpensive solution remained in use even into the 19th century. Charles Tully's Tutor for the French Horn, published in London, recommended this system for beginners as late as 1840.

The master crook and coupler system presented some problems. In high keys the instrument was uncomfortably close to the face, while in low keys, so many pieces needed to be added that the instrument could become unstable, adversely affecting the accuracy of the playing. Moreover, the instrument became so long that it was sometimes difficult to reach the bell for hand-stopping, a technique for lowering the pitch of individual notes a semitone or more. This important innovation had been introduced around 1720, and codified by Anton Hampel of Dresden in about 1750, so that the horn could be played chromatically.